Add internals for mount path

src/diff/children.js

@@ -11,6 +11,7 @@ import { isArray } from '../util';
 import { getDomSibling } from '../component';
 import { mount } from './mount';
 import { insert } from './operations';
+import { createInternal } from '../tree';
 
 /**
  * Diff the children of a virtual node
@@ -103,9 +104,11 @@ export function diffChildren(
 				refQueue
 			);
 		} else {
+			// TODO: temp
+			const internal = createInternal(childVNode, null);
 			result = mount(
 				parentDom,
-				childVNode,
+				internal,
 				globalContext,
 				namespace,
 				excessDomChildren,

src/diff/mount.js

@@ -11,11 +11,22 @@ import { insert } from './operations';
 import { setProperty } from './props';
 import { assign, isArray, slice } from '../util';
 import options from '../options';
+import {
+	createInternal,
+	MODE_MATH,
+	MODE_SVG,
+	TYPE_CLASS,
+	TYPE_COMPONENT,
+	TYPE_ELEMENT,
+	TYPE_FUNCTION,
+	TYPE_INVALID,
+	TYPE_TEXT
+} from '../tree';
 
 /**
  * Diff two virtual nodes and apply proper changes to the DOM
  * @param {PreactElement} parentDom The parent of the DOM element
- * @param {VNode} newVNode The new virtual node
+ * @param {Internal} internal The backing node.
  * @param {object} globalContext The current context object. Modified by
  * getChildContext
  * @param {string} namespace Current namespace of the DOM node (HTML, SVG, or MathML)
@@ -31,7 +42,7 @@ import options from '../options';
  */
 export function mount(
 	parentDom,
-	newVNode,
+	internal,
 	globalContext,
 	namespace,
 	excessDomChildren,
@@ -40,22 +51,24 @@ export function mount(
 	isHydrating,
 	refQueue
 ) {
+	// @ts-expect-error
+	const newVNode = internal.vnode;
+
 	// When passing through createElement it assigns the object
 	// constructor as undefined. This to prevent JSON-injection.
-	if (newVNode.constructor !== UNDEFINED) return null;
+	if (internal.flags & TYPE_INVALID) return null;
 
 	/** @type {any} */
-	let tmp,
-		newType = newVNode.type;
+	let tmp;
 
 	if ((tmp = options._diff)) tmp(newVNode);
 
-	if (typeof newType == 'function') {
+	if (internal.flags & TYPE_COMPONENT) {
 		try {
 			let c,
-				newProps = newVNode.props;
-			const isClassComponent =
-				'prototype' in newType && newType.prototype.render;
+				newProps = internal.props,
+				newType = /** @type {ComponentType} */ (internal.type);
+			const isClassComponent = !!(internal.flags & TYPE_CLASS);
 
 			// Necessary for createContext api. Setting this property will pass
 			// the context value as `this.context` just for this component.
@@ -69,11 +82,17 @@ export function mount(
 
 			// Instantiate the new component
 			if (isClassComponent) {
-				// @ts-expect-error The check above verifies that newType is suppose to be constructed
-				newVNode._component = c = new newType(newProps, componentContext); // eslint-disable-line new-cap
+				internal._component =
+					newVNode._component =
+					c =
+						// @ts-expect-error The check above verifies that newType is suppose to be constructed
+						new newType(newProps, componentContext); // eslint-disable-line new-cap
 			} else {
-				// @ts-expect-error Trust me, Component implements the interface we want
-				newVNode._component = c = new BaseComponent(newProps, componentContext);
+				// @ts-expect-error The check above verifies that newType is suppose to be constructed
+				internal._component =
+					newVNode._component =
+					c =
+						new BaseComponent(newProps, componentContext);
 				c.constructor = newType;
 				c.render = doRender;
 			}
@@ -156,6 +175,7 @@ export function mount(
 			let renderResult = isTopLevelFragment ? tmp.props.children : tmp;
 
 			oldDom = mountChildren(
+				internal,
 				parentDom,
 				isArray(renderResult) ? renderResult : [renderResult],
 				newVNode,
@@ -200,7 +220,7 @@ export function mount(
 		}
 	} else {
 		oldDom = newVNode._dom = mountElementNode(
-			newVNode,
+			internal,
 			globalContext,
 			namespace,
 			excessDomChildren,
@@ -217,7 +237,7 @@ export function mount(
 
 /**
  * Diff two virtual nodes representing DOM element
- * @param {VNode} newVNode The new virtual node
+ * @param {Internal} internal The new virtual node
  * @param {object} globalContext The current context object
  * @param {string} namespace Current namespace of the DOM node (HTML, SVG, or MathML)
  * @param {Array<PreactElement>} excessDomChildren
@@ -228,19 +248,21 @@ export function mount(
  * @returns {PreactElement}
  */
 function mountElementNode(
-	newVNode,
+	internal,
 	globalContext,
 	namespace,
 	excessDomChildren,
 	commitQueue,
 	isHydrating,
 	refQueue
 ) {
+	// @ts-expect-error
+	const newVNode = internal.vnode;
 	/** @type {PreactElement} */
 	let dom;
 	let oldProps = EMPTY_OBJ;
-	let newProps = newVNode.props;
-	let nodeType = /** @type {string} */ (newVNode.type);
+	let newProps = internal.props;
+	let nodeType = /** @type {string} */ (internal.type);
 	/** @type {any} */
 	let i;
 	/** @type {{ __html?: string }} */
@@ -252,8 +274,8 @@ function mountElementNode(
 	let checked;
 
 	// Tracks entering and exiting namespaces when descending through the tree.
-	if (nodeType === 'svg') namespace = 'http://www.w3.org/2000/svg';
-	else if (nodeType === 'math')
+	if (internal.flags & MODE_SVG) namespace = 'http://www.w3.org/2000/svg';
+	else if (internal.flags & MODE_MATH)
 		namespace = 'http://www.w3.org/1998/Math/MathML';
 	else if (!namespace) namespace = 'http://www.w3.org/1999/xhtml';
 
@@ -277,7 +299,7 @@ function mountElementNode(
 	}
 
 	if (dom == null) {
-		if (nodeType === null) {
+		if (internal.flags & TYPE_TEXT) {
 			return document.createTextNode(newProps);
 		}
 
@@ -298,7 +320,7 @@ function mountElementNode(
 		excessDomChildren = null;
 	}
 
-	if (nodeType === null) {
+	if (internal.flags & TYPE_TEXT) {
 		// During hydration, we still have to split merged text from SSR'd HTML.
 		dom.data = newProps;
 	} else {
@@ -361,6 +383,7 @@ function mountElementNode(
 			newVNode._children = [];
 		} else {
 			mountChildren(
+				internal,
 				dom,
 				isArray(newChildren) ? newChildren : [newChildren],
 				newVNode,
@@ -416,6 +439,7 @@ function doRender(props, _state, context) {
 
 /**
  * Diff the children of a virtual node
+ * @param {Internal} internal The DOM element whose children are being
  * @param {PreactElement} parentDom The DOM element whose children are being
  * diffed
  * @param {ComponentChildren[]} renderResult
@@ -435,6 +459,7 @@ function doRender(props, _state, context) {
  * @param {any[]} refQueue an array of elements needed to invoke refs
  */
 function mountChildren(
+	internal,
 	parentDom,
 	renderResult,
 	newParentVNode,
@@ -517,10 +542,11 @@ function mountChildren(
 		childVNode._parent = newParentVNode;
 		childVNode._depth = newParentVNode._depth + 1;
 
+		const childInternal = createInternal(childVNode, internal);
 		// Morph the old element into the new one, but don't append it to the dom yet
 		const result = mount(
 			parentDom,
-			childVNode,
+			childInternal,
 			globalContext,
 			namespace,
 			excessDomChildren,
@@ -544,9 +570,13 @@ function mountChildren(
 			firstChildDom = newDom;
 		}
 
-		if (typeof childVNode.type != 'function') {
+		if (childInternal.flags & TYPE_ELEMENT || childInternal.flags & TYPE_TEXT) {
 			oldDom = insert(childVNode, oldDom, parentDom);
-		} else if (typeof childVNode.type == 'function' && result !== UNDEFINED) {
+		} else if (
+			(childInternal.flags & TYPE_FUNCTION ||
+				childInternal.flags & TYPE_CLASS) &&
+			result !== UNDEFINED
+		) {
 			oldDom = result;
 		} else if (newDom) {
 			oldDom = newDom.nextSibling;

src/internal.d.ts

@@ -159,6 +159,43 @@ declare global {
 		_flags: number;
 	}
 
+	/**
+	 * An Internal is a persistent backing node within Preact's virtual DOM tree.
+	 * Think of an Internal like a long-lived VNode with stored data and tree linkages.
+	 */
+	export interface Internal<P = {}> {
+		type: string | ComponentType<P>;
+		/** The props object for Elements/Components, and the string contents for Text */
+		props: (P & { children: ComponentChildren }) | string | number;
+		key: any;
+		ref: Ref<any> | null;
+
+		/** Bitfield containing information about the Internal or its component. */
+		flags: number;
+		/** Polymorphic property to store extensions like hooks on */
+		data: object | PreactNode;
+		/** The function that triggers in-place re-renders for an internal */
+		// rerender: (internal: Internal) => void;
+
+		/** children Internal nodes */
+		_children: Internal[];
+		/** next sibling Internal node */
+		_parent: Internal;
+		/** most recent vnode ID */
+		_vnodeId: number;
+		/**
+		 * Associated DOM element for the Internal, or its nearest realized descendant.
+		 * For Fragments, this is the first DOM child.
+		 */
+		/** The component instance for which this is a backing Internal node */
+		_component: Component | null;
+		/** This Internal's distance from the tree root */
+		_depth: number | null;
+		/** Callbacks to invoke when this internal commits */
+		_commitCallbacks: Array<() => void>;
+		_stateCallbacks: Array<() => void>; // Only class components
+	}
+
 	export interface Component<P = {}, S = {}> extends preact.Component<P, S> {
 		// When component is functional component, this is reset to functional component
 		constructor: ComponentType<P>;

src/render.js

@@ -4,6 +4,7 @@ import { createElement, Fragment } from './create-element';
 import options from './options';
 import { slice } from './util';
 import { mount } from './diff/mount';
+import { createInternal } from './tree';
 
 /**
  * Render a Preact virtual node into a DOM element
@@ -28,6 +29,7 @@ export function render(vnode, parentDom, replaceNode) {
 	let oldVNode = isHydrating ? null : parentDom._children;
 
 	vnode = parentDom._children = createElement(Fragment, null, [vnode]);
+	const internal = createInternal(oldVNode || vnode, null);
 
 	// List of effects that need to be called after diffing.
 	let commitQueue = [],
@@ -51,9 +53,7 @@ export function render(vnode, parentDom, replaceNode) {
 	} else {
 		mount(
 			parentDom,
-			// Determine the new vnode tree and store it on the DOM element on
-			// our custom `_children` property.
-			vnode,
+			internal,
 			EMPTY_OBJ,
 			parentDom.namespaceURI,
 			parentDom.firstChild ? slice.call(parentDom.childNodes) : null,

src/tree.js

@@ -0,0 +1,70 @@
+import { UNDEFINED } from './constants';
+
+export const TYPE_TEXT = 1 << 0;
+export const TYPE_ELEMENT = 1 << 1;
+export const TYPE_CLASS = 1 << 2;
+export const TYPE_FUNCTION = 1 << 3;
+export const TYPE_INVALID = 1 << 6;
+export const TYPE_COMPONENT = TYPE_CLASS | TYPE_FUNCTION;
+
+export const MODE_SVG = 1 << 4;
+export const MODE_MATH = 1 << 5;
+const INHERITED_MODES = MODE_MATH | MODE_SVG;
+
+/**
+ *
+ * @param {VNode} vnode
+ * @param {Internal | null} parentInternal
+ * @returns {Internal}
+ */
+export function createInternal(vnode, parentInternal) {
+	let flags = parentInternal ? parentInternal.flags & INHERITED_MODES : 0,
+		type = vnode.type;
+
+	if (vnode.constructor !== UNDEFINED) {
+		flags |= TYPE_INVALID;
+	} else if (typeof vnode == 'string' || type == null) {
+		// type = null;
+		flags |= TYPE_TEXT;
+	} else {
+		// flags = typeof type === 'function' ? COMPONENT_NODE : ELEMENT_NODE;
+		flags |=
+			typeof type == 'function'
+				? type.prototype && type.prototype.render
+					? TYPE_CLASS
+					: TYPE_FUNCTION
+				: TYPE_ELEMENT;
+
+		if (flags & TYPE_ELEMENT && type === 'svg') {
+			flags |= MODE_SVG;
+		} else if (
+			parentInternal &&
+			parentInternal.flags & MODE_SVG &&
+			parentInternal.type === 'foreignObject'
+		) {
+			flags &= ~MODE_SVG;
+		} else if (flags & TYPE_ELEMENT && type === 'math') {
+			flags |= MODE_MATH;
+		}
+	}
+
+	return {
+		type,
+		props: vnode.props,
+		key: vnode.key,
+		ref: vnode.ref,
+		data:
+			flags & TYPE_COMPONENT
+				? { _commitCallbacks: [], _context: null, _stateCallbacks: [] }
+				: null,
+		flags,
+		// @ts-expect-error
+		vnode,
+		// TODO: rerender
+		_children: null,
+		_parent: parentInternal,
+		_vnodeId: vnode._original,
+		_component: null,
+		_depth: parentInternal ? parentInternal._depth + 1 : 0
+	};
+}